Radiant energy meter and method of making



May 20, 1941- H. c. RENTscHLER ETAL 2,242,483

`RADIANT ENERGY METER AND METHOD OF MAKING Filed June 17, 1939 2 Sheets-Sheet 1 ATTORNEY May 20, 1941. H. c. RENTscHLER ETAL RADIANT ENERGY METER AND METHOD 0F MAKING Filedv June 17, 1939 2 Sheets-Sheet 2 Patented May 20, 1941 2,242,483 RADIAN T ENERGY NEETER AND METHOD OF MAKING Orange, and Donald E.

Harvey C. Rentschler, East J., assignors to West- Henry, Cedar Grove, N.

inghouse Electric & Manufacturing Company,

East Pittsburgh, Vania Application June 17,

16 Claims.

This invention relates to a meter for measuring radiant energy and, more particularly, to one which is especially adapted for measuring the total quantity of ultra-violet radiations received Pa., a corporation of Pennsyl- 1939, Serial No. 279,662

(Cl. Z50-172) Figure 8 is a view illustrating a position vof the parts when a tube, as in Figures 1, `2 and 3, is about to be sealed, when constructed in accordance with modification of Figure 7.

thereby. V 5 Figure 9 is a view of a tube such as shown in The principal object of our invention, gener- Figures 1, 2 and 3, with the stem taped and proally considered, is the avoidance of leakage in vided with an extension cord for transmitting and over the surface of the condenser and relay energizing current to the same. tube employed with a photoelectric tube and the One of the most serious troubles with radiant connections between these in the measurement energy meters, Such as described and claimed in of radiant energy. the Rentschler Patent-No. 2,037,925`of April 21,

Another object of our invention is the produc- 1936, owned by the assignee of the present aption of a combined photoelectric tube, relay tube, plication, has been the leakage in and over the and condenser, with all the parts enclosed in an surface of the relay tube and the condenser used envelope to protect them from moisture, in order l5 in the input circuit. To obviate this trouble, we

to avoid leakage in and over the surface of said have provided a photoelectric tube, the envelope parts, and to improve the accuracy in the measof which encloses said relay tube and condenser urement of radiations. to keep moisture and air therefrom.

A further object of our invention is the pro- The leads from the photoelectric tube proper duction of an improved photoelectric tube and project into a hollow neck of the bulb -or tube associated parts, whereby greater accuracy in through a partition beneath, or separating the the measurement of radiations is obtainable. bulb from said neck. In the neck portion below A still further object of our invention is an or beyond the partition are placed the condenser improved method of manufacturing photoelecand relay tube which have been carefully treated tric tubes.l for leakage. This neck portion, forming a lower An additional object of our invention is the or outer compartment, is then exhausted and production of apparatus for measuring radiasealed oi so that moisture from the air cannot tions with greaterv accuracy than was heretofore cause trouble.

l obtaname, Now referring to the drawings in detail, like Other objects and advantages of the invention, parts being designated by like reference charrelating to the particular arrangement and convacters, and first considering the photoelectric struction of the various parts, will become aptube shown in Figures l, 2 and 3, there is proparentasthe description proceeds. vided an envelope Il, desirably composed of a Referring to the drawings: material such as Corning #97 2 high transmission Figure 1 is an elevational view of a photoelec- 35 glass, if the tube is to measure ultra-violet raditric tube embodying our invention. ations. If the tube is to measure other than Figure 2 is a transverse sectional View on the ultra-violet radiations, it is, of course, formed of line II-II of Figure 1, in the direction of the a material pervious to the type of radiations to arrow be measured.Y Other material suitable for the Figure 3 is a Vertical sectional view of the i0A transmission of ultra-violet radiations are quartz lower or neck portion of the tube shown in Figand Corex glass, but for measuring the radiaure 1. tions in the bactericidal range, Corning #972 Figure 4 is a diagram of the circuit employed glass is particularly appropriate, and the tube of in measuring radiations by means of the tube the present embodiment is especially adapted for illustrated in the preceding figures. that purpose.

Figure 5 is a view showing the position of the Within the main, bulbous or enlarged, portion parts at an early stage in the assembly of the of the envelope Il is mounted a, rod-shaped tube of Figures 1, 2 and 3. anode l2 and a cathode I3. The anode l2 may Figure 6 illustrates the position of the parts at be composed of titanium, if the tube is to be used a subsequent stage in the assembly. like that of the Rentschler Patent No. 1,955,608

Figure 7 is a view illustrating the position of of April 17, 1934, owned by the assignee 0f the the parts at an early stage in the assembly of present application, for the measurement of a tube, like that of Figures 1, 2 and 3, but in `ultra-violet radiations between about 2500 and which said parts are slightly modified as com- 3100 A. U.

pared with the showing in Figures 5 and 6. 55 1f the tube, which we will now specically conradiations of other wavelengths. The anode I2 is mounted upon a lead-in conductor I4 extending through the press I to an external conductor I6. 'I 'he conductor I4 is desirably enclosed in a dielectric shield member I1, constructed of glass or similar material. The upper portion of said shield member I1 and the joint between the anode I2 and the lead-in conductor I4, 'is also desirably enclosed in a shield member 30, desirably formed of lavite or similar insulating material, fitting the member II and having an aperture in its upper end, through which the anode I2 extends, which restricts the active area of the anode I2 to the end portion. Thus, the exposed end only of the anode need be formed of tantalum or other photoelectric material. selected.

The active cathode portion I3 preferably comprises a lm of tantalum, but may Vcomprise a lm of some other photoelectric material, if desired. Such a film is desirably deposited upon an electrical conductor, preferably formed of a sheet of nickel I8, which is electrically connected to leading-in conductor I9 passing through the press I5 as illustrated.

A framework, consisting of two parallel longitudinally extending wires 2I and 22, and a bracing cross-wire 23, is mounted above the press I5 |by means of a carryingV collar 24 frictionally engaging the fiare tube 20,-on which the press I5 is formed, as by being clamp-ed thereon by a 'bolt 25 and nut 26, the formerof which passes through overlapping flanges 2'I and 28 onL said collar. Y

Supported on this framework, is the semicylindrical nickel sheet I8 carrying the cathode surface I3. Slidable on the wiresl 2 (I and 22 is a cylindrical shield 29 adapted to enclose the anode I2, and said niclkel sheet ,I8, The wires 2| and 22 desirably pass through straps or eyelets 3| and 32 in said cylindrical shield, in order to guide the same in its sliding movement therealong. By inverting the envelope I I, the shield 29 may be moved from oneY end of the frame to the other, that is, from the lower or illustrated position where it surrounds the press I5, to its uppermost position where it surrounds the cathode I3 and enclosed anode I2.

The function of the shield 29is to protect the walls of the envelope from vaporized orsputtered tantalum, or other cathode-activating material,

during the electrical sputtering from the anode to form said cathode.

In order to obtain the photosensitive cathode, the electrode assembly is sealed to the envelope and the whole desirably inverted, baked out and exhausted, in the usual manner heretofore em- With the tube inverted and the shield 29 about the electrodes I 2 and I3, a glow discharge of suicient current density to effect positive ion bombardment of the electrode I2, is created from the electrode I3, and a sputtering or electrical vaporization of the material or tantalum of the electrode I2 to the sheet I8 of nickel, occurs, until a uniform cathode surface having the proper spectral sensitivity is formed.

A direct current discharge is employed and the rod I2 serves asy a cathode, while the sheet I8 of nickel serves as the anode for said discharge.

' The glow discharge should be continued until a ployed to obtain high vacua, and the shield 29 is degasied by heat, provided by high frequency induction, for example. A filling of a gaseous medium, such as argon, neon or helium is then l introduced into the envelope in any convenient manner, as through the exhaust tube 33. Argon gas at a pressure of from about 1 to 6 min. is preferably employed, and the envelope then sealed off. i

sucient deposit of tantalum or other .photosensitive material, is obtained upon the surface of the sheet of nickel I8, to render the same photoelectrically sensitive. We find it preferable to continue the discharge for about twenty hours, the exact length of time, however, depending upon conditions. The sputtered material, other than that deposited upon the sheet of nickel I8, mainly collects on the interior of the shield 29, and the shields 34 and 35, the former of which is carried by lead-in conductor I9 and the latter by spud 35 extending from the press I5, in order to maintain clear areas around where cathodeconnected wires enter the press and thereby prevent short circuiting between the anode I2 and cathode I3 of said tube. ASome sputtered material may escape fromthe open ends of the shield 29, but it would tend to fall on areas not needed for transmitting the radiations to be measured.

After the cathode I3 has been thus formed. the shield 29 is moved back to the position illustrated in Figure 1, where it is desirably maintained, except when shaken .back to the top of the tube, by means of spring wire 31 which extends from a support held by the press I5, such as the spudy 36, outwardly into engagement with the inner surface of said shield 29, when the latter is in the lowermost position illustrated. The main portion of the envelope II may then be finally exhausted, without opening to the atmosphere, by a method formerly used. If argon was used as the gas filling, said main portion desirably had apparatus connected to it, like the tube 20 of our copending application, Serial No. 102,641, filed Sept. 26, 1936, now Patent No. 2,167,777, dated August 1, 1939, and Could be nally exhausted by means of activated charcoal in liquid air, to make a vacuum photocell.

A relay tube 39 and a condenser 4I are housed in the neck or extension 38 of the envelope II, as illustrated most clearly in Figure 3. The relay tube 39 is desirably formed as described and claimed in the Rentschler Patent No. 2,079,362 of May 4, 1937, and owned by -the assignee of the present application, except that it is not necessary to base it. That is, the tube comprises an envelope 42 of glass or the like and three electrodes supported from the stem 43 thereof, the electrode 44 desirably formed of thorium vand functioning as a cathode, electrode 45 as the main anode, and electrode 46 as the starting or auxiliary anode.

Although all of these electrodes are supported from the stem or press 43, as by means of support wires 41, 48 and 49, the starting anode 46 has its outside connection desirably made by means of lead-in conductor 5I extending through the end portion of the tube or envelope 42 opposite to that to which the stem or press 43 is secured. Before sealing the relay tube 39 and the condenser 4I in the extension 38, both are desirably 'sealing wax shown, in order to prevent surface leakage. As alternatives the envelope 42 of the relay tube may be painted with a light-absorbing coating 53, or formed of red or green glass, which is sufficiently light absorbing, as the thorium cathode is not photosensitive to wave lengths much longer than 3650 A. U., While the other parts from which the leads extend, are coated with sealing wax.

The condenser and relay tube do not have to be coated with sealing wax if the leakage during calibration is negligible, as moisture due to sealing-in can be removed in the exhaust.

The connections between the electrodes I2 and I3 in the photoelectric tube compartment proper and the leads to the relay tube and condenser in the extension or auxiliary tube 38, are as shown in Figures 1 and 3, and in accordance with the diagram in Figure 4.

The cathode I3 is connected by means of leadin conductor I9, coil spring 54 and lead 55 to the lead 56, which connects one pole of the condenser 4I to the lead-in conductor 5I from the starting anode 46. The other pole of the condenser is connected by means of lead 51 to cathvode 44, and a lead 60 from said connection extends through flare or press 58 of extension 38, out of the envelope II, forming one of the terminals of the combination photoelectric tube.

Another terminal of the tube connects with the main anode 45 of the relay tube 39 by means of lead 58 extending through the same press 58, while the third terminal connects with the anode I2 of the photoelectric tube proper by means of supporting portion I4, lead I6, coil spring 6I, and lead 62 through the same press 58.

It will thus be seen that `the anode I2 of the radiation-responsive device disclosed is, when assembled for use, as diagrammatically shown in Figure 4, connected through leads I6 and 62 to the positive terminal of a source of potential, for example, a battery of cells 63. The negative terminal of said source of potential is connected by means of lead 60 to one side of condenser 4I, While the other side is connected Ito the cathode I3 by means of leads 56, 55 and I9, as well as to the starting anode 46 of the relay tube by means of leads 56 and 5I. The cathode 44 of the glow relay tube 39 is also connected Ito said negative pole of the battery 63, by means of conducto-rs 51 and 60, thereby completing the input circuit to said relay tube 39 in accordance with the Rentschler Patent No. 2,037,925, previously referred The output circuit of the system shown in Figure 4 comprises a xed or variable resistance 64 of appropriate value, having one end thereof connected to the positive terminal of one of the cells in the battery 63, and -the other end of which is connected to one terminal of a recording device 65 and one pole of a condenser 66. The other pole of the condenser 66 is connected to the lead 66, as shown most clearly in Figure 4. The other terminal of the recording device 65 is connected to the anode 45 of the relay tube 33 as by means of lead-in conductor 59.

From the foregoing disclosure, it will be seen that .all of the parts of the input circuit, shown in the diagram of Figure 4, are enclosed in the extended evacuated envelope I I and thereby kept moisture-free'and protected from leakage, except the energizing battery 63. The operation of the device for the measuring of radiations is las described and claimed in the Rentschler Patent No.

as shown in Figure 8.

2,037,925, previously referred to, except that, by virtue of enclosing the .parts of the 4input circuit for protection against leakage due to moisture, the accuracy of the measurement is greatly increased.

It will be seen that the main difference in the photoelectric portion of the combined device, is that the lead I9 from the cathode I3 goes through the stem or lower part of the enlarged or bulbous portion .of the envelope II, rather than through the upper portion. In order, however, to test the photoelectric portion of Ithe combined tube, separately from the associated condenser 4I and relay tube 39, after the parts are assembled as a unit, we :desirably also provide a lead 61" extending through the upper portion of the envelope II and having a` coil spring 68 housed in a tubular extension 69. That portion of the lead 61 between the seal 1I `and the cross wire 23 is desirably a coil of soft wire 12 to prevent strain in the seal 1I and allow the lead 61 to be properly positioned for sealing-in at 1I. The spring 68 desirably carries an eyelet 13 at its outer end, so that it may be grasped and pulled out of the enclosing Itube 59 for connection with a testing circuit. After testing the photoelectric portion, the spring 68 may be allowed to contract to the position illustrated, and the tube 68 sealed at 14 and covered by a' protective housing 15.

In manufacturing a combined meter device such as heretofore disclosed, the photoelectric tube portionis exhausted, the anode sputtered to provide the sensitive cathode surface, and the envelope re-exhausted as previously described. The tube is then tested for the spectral position of the energy cutoff, after which it may be exposed to .the radiations from a suitable source, with the lead I9 connected to Ithe top of the relay tube 38 in the regular meter circuit, and the lead I6 connected to the positive side of the battery. Arrangements should be'made so that the condenser 4I, between the top of the relay tube 39 and the negative side of the battery 63, can be changed at will until one is found of such capacity that energy unit indicating clicks of the recorder come at the desired intervals.

When a condenser having the proper capacity is found, it and the relay tube are mounted on the flare 58, as shown in Figure 3. A spring is welded to each of the leads I6 and I9 coming from the photoelectric portion, in such a manner that their ends can be pulled past the end v 38. The relay tube and condenser, mounted on the flare 58, are pushed up into the neck 38, but the flare held far enough out so that the springs 54 and 6I can be pulled down and welded to the leads 55 and 62.

Positions in making the foregoing assembly are illustrated in Figures 5 to 8, inclusive. Figure 5 shows the envelope II and the flare 20 carrying the photoelectric assembly on its way up the neck 38 toward the enlarged portion of said envelope II.

Figure 6 shows photoelectric anode I2 of the extended neck the flare 20 and the supported and cathode I3 in vplace in the envelope II, and fires 16 being employed to fuse the flare 20 to the extension 38 at the proper place .along its length. The springs 54 and 6I are, in this figure, shown pulled down and Welded to the leads 55 and 62. After this has been accomplished, the flare 58 is inserted into the neck 38, and its peripheral ange sealed to the Outer end thereof, using the sealing res 18, The extension containing CFI the extension 38b may be out 01T as indicated by the dotted line 82, and the subsequent formation of the device may then be in accordance with Figures 6 and 8, as described in connection with the other embodiment.

After sealing, as shown in Figure 8, the neck 38 is well exhausted, warmed slightly with a torch, being careful not to get too close to where the neck is sealed on to the bulb of the envelope Il, and after thorough exhausting, said neck portion is tipped off as at 33.

After the device is completely assembled and tested, the tubular extension 38, or 38e-38h, as the case may be, is desirably covered by protective tape 84, as shown in Figure 9, and provided with an extension cord 85.

From the foregoing, it will be seen that by virtue of the compartment 38, containing the relay tube and condenser, being hermetically sealed from the main or bulbous compartment of the envelope II, lthe degrees of exhaust in the two compartments do not need to correspond. It is, therefore, feasible to make a vacuum type photoelectric tube or one of the gaseous type, as desired, without regard to the degree of vacuum in the neck compartment 38.

Although preferred embodiments of our invention have been disclosed, it will be understood that modications may be made within the spirit and scope of the appended claims, and that the envelope Il may be generali;7 cylindrical or have a shape other than that illustrated, if desired.

We claim:

1. A photoelectric device comprising an envelope consisting of a tubular portion and another portion, a cathode disposed in said other por-tion and sensitive to radiations to be measured, said other portion being permeable to such radiations, an anode mounted in cooperative relationship with said cathode, and a relay tube and condenser in said tubular portion.

2. A photoelectric device comprising an envelope consisting of a tubular portion Iand an enlarged bulbous portion, a cathode disposed in said enlarged portion and sensitive .t-o radiations to be measured, said enlarged portion being permeable to such radiations, an anode mounted in cooperative relationship with said cathode, and a rel-ay tube and condenser in said tubular portion.

3. A photoelectric device comprising an envelope consisting of a tubular portion and another portion, a tantalum sensitized cathode disposed in said other portion, an anode mounted in cooperative relationship with said cathode, said other portion being permeable to substantially all bactericidal radiations below 3000 Angstrom units, and a relay tube and condenser in said tubular portion.

4. A photoelectric device comprising an envelope consisting of a tubular portion and an enlarged bulbous portion, a tantalum sensitized cathode disposed in said enlarged, portion, any

anode mounted in cooperative relationship with said cathode, said enlarged portion being-permeable to substantially all bactericidal radiations below 3000 Angstrom units, and a relay tube and condenser in said tubular portion.

5. A photoelectric device comprising an envelope having two compartments hermetically sealed from each other, a .titanium sensitized cathode disposed in one compartment, an anode mounted. in cooperative relationship with said cathode, said compartment being permeable to substantially all radiations between 2700 and 3100 Angstrom units, and a relay tube and condenser mounted in said other compartment.

6. A photoelectric device comprising an envelope consisting of an exhausted tubular portion, and an enlarged bulbous portion, a cathode disposed in said enlarged portion and sensitive to radiations to be measured, an anode mounted in cooperative relation-ship with said cathode, said enlarged portion being permeable to radiations to be measured, a partition hermetically sealing said enlarged portion from said tubular portion and a relay tube and condenser in said .tubular portion.

7. A photoelectric device comprising a cathode sensitive to substantially all radiations below 3000 Angstrom units, an anode, an envelope enclosing said electrodes with at least the portion opposite the sensitive surface of said cathode penneable to radiations below 3000 Angstrom units, and a relay tube and condenser also sealed in said envelope, but separated from said electrodes by a partition.

8. A photoelectric device comprising a cathode sensitive to substantially all radiations between 2700 and 3100 Angstrom units, an anode, an envelope enclosing said electrodes with at least the portion opposite the sensitive surface of said cathode permeable to radiations below 3200 Angstrom units, and a relay tube and condenser also sealed in said envelope, but separated from said electrodes by a partition.

9. A photoelectric device comprising an elongated envelope, a cathode disposed in one end portion and sensitive to radiations to be measured, a-n anode mounted in cooperative relationship with said cathode, said end portion being permeable to radiations to be measured, a are tube separating the portion of said tube containing said cathode and anode from the remainder and supporting said electrodes, and a relay tube and condenser in the other portion of said envelope.

10. A photoelectric device comprising an envelope having a main portion and an elongated neck portion, a light-sensitive cathode disposed in said main portion, an anode mounted in cooperative relationship with said cathode, both of said elements being supported from a flare tube the peripheral portion of which is hermetically sealed to said neck portion in order to divide said envelope into said main and elongated portions, and an associated condenser and relay tube mounted on a are tube hermetically sealing the outer end of said neck portion, said neck portion being exhausted to keep said condenser and relay tube free from moisture.

11. A photoelectric device comprising an envelope consisting of a main portion with an elongated neck extending therefrom, photoelectric elements mounted on a are tube and supported in the main portion of said envelope, said flare tube serving to hermetically seal the outer portion of said neck therefrom, leads extending through a press on said are tube and terminating in springs, a condenser and relay tube mounted on another flare tube and electrically connected to said photoelectric elements by said springs, in order to allow for connection outside of said neck and subsequent insertion therein, said condenser and relay tube flare tube serving to hermetically seal the outer end of said neck.

12. A photoelectric device, comprising a cathode sensitive to radiations to be measured, an anode mounted in cooperative relationship with said cathode, a relay tube and a condenser, and a single evacuated envelope enclosing all of said elements.

13. A photoelectric device, including as elements, a cathode and an anode of photoelectric means connected to a relay tube and condenser, and a common evacuated envelope enclosing all of said elements, said condenser being connected across the starting anode and the cathode of said relay tube, and the pole of said condenser which is connected to said starting anode, being also connected to said photoelectric cathode.

14. A photoelectric device comprising an envelope consisting of a main bulb portion with an elongated neck extending therefrom, photoelectric elements mounted on a flare tube, hermetically sealed to said neck portion, and extending into said bulb portion, a rare gaseous atmosphere in said bulb portion, leads extending through said flare tube and terminating in springs, and a condenser and relay tube mounted on another flare tube and electrically connected to said springs in order to allow for connection outside of said neck and subsequent insertion therein, said other flare tube serving to hermetically seal the outer end of said neck, and the latter being evacuated between said are tubes, in order to keep the condenser and relay tube free from moisture.

15. A photoelectric device comprising a single envelope hermetically divided into two compartments by a are tube, a cathode sensitive to radiations to be measured and a cooperating anode sealed in one of said compartments, a relay tube and a condenser sealed in said other compartment, electrical connections between said cathode and anode and said relay tube and condenser, terminals to said anode, condenser and relay tube extending out of said other compartments, and a second conductor for testing purposes extending from said cathode out of the first-mentioned compartment.

16. A photoelectric device, comprising a cathode sensitive to radiations to be measured and a cooperating anode mounted in one compartment of an envelope, and a connected relay tube and condenser mounted in another compartment, said compartments being hermetically sealed from one another and the atmosphere and eX- hausted to different degrees of vacuum.

HARVEY C. RENTSCHLER. DONALD E. HENRY. 

